[ASan] reimplement strdup() interceptor to get nicer stack traces for memory chunks allocated there

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@184546 91177308-0d34-0410-b5e6-96231b3b80d8
[asan] Move lsan_disabled out of thread context.

Fix for the case where disabler is used in pthread key destructor.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@184553 91177308-0d34-0410-b5e6-96231b3b80d8